package chapter10.eg10;

import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
import static io.netty.handler.codec.http.HttpResponseStatus.FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
import static io.netty.handler.codec.http.HttpResponseStatus.METHOD_NOT_ALLOWED;
import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelProgressiveFuture;
import io.netty.channel.ChannelProgressiveFutureListener;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpUtil;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.LastHttpContent;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Pattern;
import javax.activation.MimetypesFileTypeMap;

public class HttpFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

  private final String url;

  public HttpFileServerHandler(String url) {
    this.url = url;
  }

  @Override
  protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
    if (!request.decoderResult().isSuccess()) {
      sendError(ctx, BAD_REQUEST);
      return;
    }

    if (request.method() != HttpMethod.GET) {
      sendError(ctx, METHOD_NOT_ALLOWED);
      return;
    }

    final String uri = request.uri();
    final String path = sanitizeUri(uri);
    if (path == null) {
      sendError(ctx, FORBIDDEN);
      return;
    }

    File file = new File(path);
    if (file.isHidden() || !file.exists()) {
      sendError(ctx, NOT_FOUND);
      return;
    }

    if (file.isDirectory()) {
      if (uri.endsWith("/")) {
        sendListing(ctx, file);
      } else {
        sendRedirect(ctx, uri + "/");
      }

      return;
    }

    if (!file.isFile()) {
      sendError(ctx, FORBIDDEN);
      return;
    }

    RandomAccessFile randomAccessFile = null;
    try {
      randomAccessFile = new RandomAccessFile(file, "r");
    } catch (FileNotFoundException e) {
      sendError(ctx, NOT_FOUND);
      return;
    }

    long fileLength = randomAccessFile.length();
    HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, OK);
    HttpUtil.setContentLength(response, fileLength);
    setContentTypeHeader(response, file);
    if (HttpUtil.isKeepAlive(request)) {
      response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
    }

    ctx.write(response);
    ChannelFuture sendFileFuture = ctx
      .write(new ChunkedFile(randomAccessFile, 0, fileLength, 8192), ctx.newProgressivePromise());
    sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
      @Override
      public void operationProgressed(ChannelProgressiveFuture future, long progress, long total)
        throws Exception {
        if (total < 0) {
          System.out.println("Transfer progress: " + progress);
        } else {
          System.out.println("Transfer progress: " + progress + " / " + total);
        }
      }

      @Override
      public void operationComplete(ChannelProgressiveFuture future) throws Exception {
        System.out.println("Transfer complete.");
      }
    });

    ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
    if (!HttpUtil.isKeepAlive(request)) {
      lastContentFuture.addListener(ChannelFutureListener.CLOSE);
    }
  }

  private String sanitizeUri(String uri) {
    try {
      uri = URLDecoder.decode(uri, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      try {
        uri = URLDecoder.decode(uri, "ISO-8859-1");
      } catch (UnsupportedEncodingException e1) {
        throw new RuntimeException("unsupported encoding!!!");
      }
    }

    if (!uri.startsWith(url)) {
      return null;
    }

    if (!uri.startsWith("/")) {
      return null;
    }

    uri = uri.replace('/', File.separatorChar);
    if (uri.contains(File.separator + ".") || uri.contains("." + File.separator)
      || uri.startsWith(".") || uri.endsWith(".") || INSECURE_URI.matcher(uri).matches()) {
      return null;
    }

    return "/Users/zhangxufeng/xufeng.zhang/workspace/mynetty" + uri;
  }

  private void sendListing(ChannelHandlerContext ctx, File dir) {
    FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, OK);
    response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html;charset=UTF-8");
    StringBuilder buf = new StringBuilder();
    String dirPath = dir.getPath();
    buf.append("<!DOCTYPE html>\r\n")
      .append("<html><head><title>")
      .append(dirPath)
      .append(" 目录：")
      .append("</title></head><body>\r\n")
      .append("<h3>")
      .append(dirPath)
      .append(" 目录：")
      .append("</h3>\r\n")
      .append("<ul>")
      .append("<li>链接：<a href=\"../\">..</a></li>\r\n");
    for (File file : dir.listFiles()) {
      if (file.isHidden() || !file.canRead()) {
        continue;
      }

      String name = file.getName();
      if (!ALLOWED_FILE_NAME.matcher(name).matches()) {
        continue;
      }

      buf.append("<li>链接：<a href=\"")
        .append(name)
        .append("\">")
        .append(name)
        .append("</a></li>\r\n");
    }
    buf.append("</ul></body></html>\r\n");
    ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);
    response.content().writeBytes(buffer);
    buffer.release();
    ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
  }

  private void setContentTypeHeader(HttpResponse response, File file) {
    MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
    response.headers()
      .set(HttpHeaderNames.CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
  }

  private void sendRedirect(ChannelHandlerContext ctx, String path) {
    FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, FOUND);
    response.headers().set(HttpHeaderNames.LOCATION, path);
    ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
  }

  private void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
    FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, status,
      Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
    response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain;charset=UTF-8");
    ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);

  }

  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    cause.printStackTrace();
    if (ctx.channel().isActive()) {
      sendError(ctx, INTERNAL_SERVER_ERROR);
    }
  }

  private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
  private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");
}
